Vapor Phase Infiltration Modulating Microwave Absorption of Conductive Polymers: Frequency Tunability and Polarization Enhancement

ABSTRACT Conductive polymers have attracted attention as flexible and lightweight candidates for high‐performance electromagnetic wave absorbers. However, the limited tunability of the dielectric response and the underutilization of polarization loss mechanisms remain significant challenges. Here, vapor phase infiltration (VPI) is employed as an ingenious and controllable strategy for doping inorganic species into the polymer matrices and modulating dielectric behavior at the molecular scale. Using TiCl ₄ as the precursor, PEDOT:PSS‐coated polypropylene foams are infiltrated under systematically varied VPI cycles and exposure durations. Adjusting the infiltration parameters allows the permittivity to be finely tuned, resulting in a distinct low‐frequency shift of the absorption peak. The results show that prolonged exposure time promotes deeper infiltration of the precursor and the formation of nano‐scale Ti‐containing hybrid domains in the matrix, which strengthens the coupling of organic‐inorganic interfaces, thereby promoting dipole polarization and interface polarization. This study combines theoretical calculations with experiments to elucidate the intrinsic mechanism of enhanced electromagnetic wave attenuation through VPI, offering new insights for regulating the dielectric behavior of conductive polymers.